Saints couldn't find the spark they needed as they suffered a ninth defeat in 14 Aviva Premiership matches at The Rec on Friday night.
Bath bounced back after going 6-0 down to two Piers Francis penalties, and the home side eventually cruised to a 32-9 success.
Francis was to notch another three points in the second half, but it was nowhere near enough as Saints struggled to create clear scoring chances.
A sloppy piece of play saw them stung by a Matt Banahan try on the brink of half-time and that effort helped to push Bath into a 10-point lead, which Saints never threatened to overturn.
It means the black, green and gold continue their disappointing run on the road in the Premiership - they have not won an away league game since beating London Irish back in September.
Saints had gone into the game on the back of two victories in the Anglo-Welsh Cup, and they started in confident fashion. winning a couple of early penalties in the Bath half.
Fly-half Francis opted to take a shot at goal, earning his side a 3-0 lead after five minutes.
Saints were playing the game almost exclusively in the Bath half, with the home side penalised on several occasions.
And after Tom Wood charged up the middle and won another shot at goal, Francis doubled Saints' lead.
Francis was not only sharp from the tee, but his kicking to touch was putting Saints in strong positions.
However, after Bath survived a lineout drive in their own 22, the home side finally managed to put some pressure on, with Freddie Burns able to land a penalty to reduce the deficit.
And Burns was on target again to level the scores nine minutes before the break as some strong breakdown work and sharp offloading from Bath earned a second shot at goal.
Saints were continuing to concede costly penalties in their own half and Burns landed his third penalty three minutes before the break to put Bath ahead.
It had been a nip and tuck game, but Bath were now on the front foot and after Saints mounted one final attack before the break, the home side struck.
Saints' passing was far from secure and after the ball came loose, a grubber kick found Banahan, who bamboozled the helpless Ben Foden and raced in to score.
Burns put the icing on the cake with the successful conversion, taking his team 16-6 up at the break.
The bit was between the Bath teeth at the start of the second period and after they were held up over the line, Burns came back to kick another penalty.
Francis landed a kick of his own to bring the gap back to 10 points, but Saints were still struggling to find a way through the blue, black and white wall.
The away side turned to their bench, bringing Nic Groom and Harry Mallinder into the action seconds before Burns landed yet another penalty.
Saints were desperately searching for a spark, but whenever they got into Bath territory, the home side were forcing errors, meaning attacks were short-lived.
At the other end, James Wilson was starting to cause his former club problems, with the Kiwi, who was playing at full-back, finding more and more space as the game went on.
Bath continued to knock on the door and they sent prop Nick Auterac in out wide to put the game well beyond Saints.
Burns failed to add the extras, but his side were now well clear at 27-9 up, and Saints had totally lost their way.
Bath threatened to score again before the end, and they did, with replacement hooker Ross Batty bagging his team's third try of the night.
The conversion was missed but it didn't ease Saints' misery at the end of a hugely disappointing second half.
Bath; Wilson; Banahan (Atkins 52), Hurrell, Tapuai, Brew; Burns (Lewis 72), Fotuali'i (Cook 55); Noguera (Auterac 55), Dunn (Batty 62), Lahiff (Thomas 49); Stooke, Ewels (Charteris 70); Garvey (c), Grant, Phillips (Bayliss 62).
Saints: Tuala; Pisi (Tuitavake 74), Horne, Stephenson, Foden; Francis (Mallinder 57), Reinach (Groom 57); Ma'afu (van Wyk 57), Haywood (Marshall 65), Brookes (Ford-Robinson 57); Ratuniyarawa, Day (c) (Ribbans 61); Wood (Nutley 74), Gibson, Harrison.
Referee: Tom Foley